Two-wire current interfaces for pulse-width modulation (PWM) sensors are the standard for many automotive applications. For example, magnetic speed sensors are used in speed sensing for many applications in automotive industry, including wheel speed, engine speed, and transmission speed.
The automotive industry requires electronic components to pass an electromagnetic compatibility (EMC) test called RI 130. This test applies also to two-wire speed sensors, such as transmission speed sensors. In order to be able to pass this test, it has been identified that in parallel to the sensor a capacitor, typically of the size of 22 nF, has to be used. However, the use of the capacitor causes the slew rates of a current pulse generated by a PWM sensor to be degraded beyond the allowed tolerance windows specified for the automotive application (e.g., the transmission control unit).
Therefore, an improved device that can meet both the specification of the automotive application and the RI 130 test may be desirable.